Apparatus for heat-treating bimetallic strip material



Jan. 22, 1952 APPARATUS FOR Filed May 5, 1949 D. H. GARDNER 2, 83, 6

HEAT-TREATING BIMETALLIC STRIP MATERIAL 6 Sheets-Sheet l INVENTOR.jam/(Z f/ zzd/zer Jan. 1952 D. H. GARDNER 2,583,046

APPARATUS FOR HEAT-TREATING BIMETALLIC STRIP MATERIAL Filed May 5, 19496 Sheets-Sheet 2 I N VEN TOR. Jana/(Z //'a2zZ22er B Y ah;

Jan. 22, 1952 D. H. GARDNER 2,583,046 APPARATUS FOR HEAT-TREATINGBIMETALLIC STRIP MATERIAL Filed May 5, 1949 6 Sheets-Sheet 3 IN V ENTOR.

Jana/a farazer Jan. 22, 1952 D. H. GARDNER APPARATUS FOR HEAT-TREATINGBIMETALLIC STRIP MATERIAL 6 Sheets-Sheet 4 Filed May 5, 1949 v IINVENTOR. Jana/a5 AV 662/0 7-2617 Jan. 22, 1952 D. H. GARDNER APPARATUSFOR HEAT-TREATING BIMETALLIC STRIP MATERIAL Filed May 5, 1949 6Sheets-Sheet 5 INVENTOR.

Jan. 22, 1952 o. H. GARDNER 2,583,046

APPARATUS FOR HEAT-TREATING BIMETALLIC STRIP MATERIAL Filed May 5, 19496 Sheets-Sheet 6 OOOOOOOOQOPOpOOOOOOOO000000? INVENTOR.

Patented Jan. 22. 1952 2,583,046

APPARATUS FOR HEAT-TREATING BIMETALLIC s'rRIP MATERIAL Donald H.Gardner, Detroit, Mich., assignor to Sunbeam Corporation, Chicago, 11].,a corporation of Illinois Application M... a, 1949, Serial No. 91,194

13 Claims. (Cl. zes -s This invention relates to an apparatus for heattreating strips of metal material of the type such as bimetal stripsthat tend to warp when heated.

In the making of bimetal strips two ormore slabs of preselected metalare placed in side by side relation and are pressed together by asuitable pressure applied at the proper temperature. Thereafter thecomposite slab is passed through rollers a number of times until theslab is rolled out to the desired thickness; that is, it can be cut intosmall strips foruse in instruments and the like or can be readilycoiled. The characteristics of the bimetal material are such that as itis heated it tends to bend or become deflected, this of course is thebasis for its use in industry.

This inherent bending of bimetal material, when heated, presents a realproblem in handling during the annealing processes between successiverollings of the slab. Heretofore no satisfactory -means has beenavailable for handling bimetal lic material between the time it is incomposite slab form until it is of such thickness that it can be readilyused. For example the conventional electric strip annealing furnaces arenot suitable for heavy stock due to the high losses of material involvedin spot welding short strips together to produce continuous lengths. Oneof the methods widely used heretofore comprises forcibly coiling thestrips in the direction in which they would bend when heated, bindingthem with wire to prevent uncoiling and then loading the bound coils/into baskets for immersion into oil fired salt pots. To conserve spacethe strips are generally coiled in decreasing diameter so that one coilcan be loaded or supported inside another coil and together thecoilsform a comparatively solid unit. Several of these solid coils are thenstacked, one upon the other in the basket After these coils have beenheated the required length of time the basket is removed from the saltpot and cooled in water to wash off the salt. The coils or strips arethen removed from the basket, the binding wire for the individual coilsremoved and the strips straightened and passed through a specialdecoiling and cleaning machine. The above process although widely usedis objectionable on several grounds. It is obvious that there are manyhazards insofar as the safety of the operating personnel is concerned.For example the unloading of the salt furnace involves danger to thepersonnel due to the fumes and splattering of the salt as the basket israised from the salt pot. The removing of the coils from the salt thesesalt pot installations are an eye sore.

pots and then subsequently placing them, in cool water is verydangerous, being almost explosive in nature. Personnel in factories inwhich salt pots have been utilized have complained of the noiseresulting from the immersion of the coils in the salt pot and cool waterand also from the fact that the buildings housing this equipmentfrequently shake rather severely during this process because of theconcussion waves resultin from the immersion of the-coils in the saltpots and water. Due to the fact that this process is inherently sodangerous factories utilizing salt pots for-this purpose have found thatthey have an extremely high labor turnover for operators of salt pots.In addition to presenting hazards to the personnel such salt pots haveconstituted a fire hazard and in general detract from the appearance ofthe factory. As a matter of fact In other instances slabs have beenstacked one on the other in a furnace with weights distributed over thetop of the stack to prevent deflection of the slabs during the heattreating thereof. Preferably, adjacent slabs are placed in side by siderelation so that the deflection of one slab counteracts that of another.This method is not satisfactory in that it requires a considerableamount of handling of the bimetal slabs both in preparing the slabs andin placing them in the furnace and in removing the slabs there fromConsiderable scaling has also been encountered withpprior heat'treatingunits. One of the big objections to previous constructions for heattreating bimetal slabs has been that they have required a large numberof operating personnel.

An object of the invention is to provide a novel annealing furnace meansfor bimetal and the like materials, that insures that the bimetal stripis uniformly annealed, that the bimetal strip has a bright finish,andprovides for the expeditious handling of the bimetal strip to.

i l I bimtifistrip or slab as itfadvances through the furnace means.

Another object of the invention is the provision of furnace means of theabove character for bimetal strips or slabs and the like that requires aminimum of operating personnel.

' Another object of the invention is to provide furnace means of theabove character wherein the operation thereof entails a minimum ofhazards to the operating personnel, both of the furnace means andadjacent equipment in a fac- .t ry.

Another object of the invention is to provide furnace means of the abovecharacter wherein the bimetal strip after passing through the furformedin a furnace IO.

the receiving end of the annealing furnace unit;

, nace per se taken along the section line '|'I in Fig. 8 is a top planview of the discharge end of the furnace unit;

Fig. 9 is a sectional view taken substantially along the line 9-9 ofFig. 10;

Fig. 10 is a side elevational view of the portion of the furnace unitshown in Fig. 8;

Fig. 1'1 is an enlarged sectional view showing the gas curtain andsealing arrangement for 4 of stock successively through the heating andcooling chambers II and [2 respectively and means for limiting orrestraining the distortion or deflection of the bimetal strip as it isheated and subsequently cooled in passing through the heat treatingunit.

The heating chamber II in this instance is The chamber H is defined by asuitable thickness of refractory material such as firebrick l1. As shownin Figs. 4 and 7 the chamber II is relatively long and has a generallyrectangular cross section with an arched top of conventionalconstruction. The bricks II are encased in suitable insulating materialI I, which in turn is'housed in a suitable housing it formed by metallicsheets suitably fastened together. The housing I9 is mounted on suitablecross members 2| spaced lengthwise of the housing and supported byspaced uprights 22 on opposite sides of the housing. The chamber IIshould be made gas tight so that an atmosphere may be introducedtherein.

While any suitable means may be provided for supplying heat to thefurnace in this instance it is shown as being heated by electricresistance units 23 and 24. In the present instance four electricresistance units are utilized, two units 23 supported at the top of thechamber II and two units 24 supported at the bottom of the chamber II.The resistance elements '23 are formed by ribbons shaped and positionedas "shown in Fig. 6 and supported on conventional insulated supportingunits 28 in turn supported by elements 28 suspended from cross members3|. The cross members 3| are suitably supported on opposite sides at thetop of the chamber I I as by ledges 30 and the side walls defining thechamber II. The ends of the heating elements 23 are connected toconductors 32. The latter project vertically through the top of thefurnace unit and terminate'in suitable terminals 33 dispreventing theleakage of gas from the furnace unit, and

Fig. 12 is a sectional view taken substantially along the line l2-l2 ofFig. 11.

Referring now to the drawings, the invention is shown embodied in a heattreating or annealing unit adapted for heat treating bimetal slabs orstrips. Such strips may consist of two or more metals laminated togetherin a conventional manner to form composite strips or slabs. In generalthese strips or slabs will vary in length from 6 to 35 feet, are A"thick, initially, and are generally somewhat less than a foot wide. Theyare rolled until the final strip may be approximately .020 inch thick orthe like, depending on the ultimate use of the strip.

While the heat treating unit to be described hereinafter is intendedprimarily for bimetal strips, it is to be understood that any other typeof strip may be used if desired particularly where the strips are thetype that distort as a result of heating the strip. Inthis embodiment ofthe invention the heat treating unit in general comprises a heatingchamber ll of suitable size to accommodate the material being handled, acooling chamber l2 of suitable size to accommodate the material beinghandled adjacent the heating chamber, means for advancing the stripposed in houses 34 mounted on top of the housing l9. In a similar mannerthe heating elements 24 are formed by ribbons shaped and positioned asshown in Fig. 6. The ribbons are supported on suitable insulatingsupports 36 mounted on transversely extending ribs 35 on the bottom ofthe chamber I I. The ends of the ribbon 24 are connected to conductors31 which project through the bottom of the housing l9 and terminate interminals 38 located in houses 39 suitably supported on the bottom ofthe housing I9. By providing four sets of elements as shown, two zonesof heating are provided in the furnace, one being used to bring thecharge in the furnace up to temperature and the other being used tosaturate the charge with heat. The temperature in the furnace may beautomatically controlled by any suitable conventional means well knownin the art. The latter is not shown for purposes of simplifying thedrawings. The power leads for connecting the resistance units in thepower system have also been omitted to simplify the drawings, it beingunderstood that' any suitable conventional conductors may be used forthis purpose.

The cooling chamber i2 is in axial alinement with the furnace and ispositioned at the discharge end thereof. The cooling chamber is definedby a plurality of sections 40 each formed as shown in Figs. 9 and 10 bytwo generally tubular members ll and 42, disposed one within the other,and each having elongated rectangular cross sections. At the ends ofeach section 40 the tubular members are joined together as by flanges42a to form a central axially extending,

passageway 43 opening on both ends oi the section and a water chamber 44closed at both ends of the section and surrounding the axially extendingpassageway 43. The sections are suitably supported on spaced rollers 45(see Fig. supported on frameworks 41 and 48. The sections 48 are rigidlysecured together by bolts extending through the flanges 42a on adjacentsections so that the axial passageways 43 are in alinement to define thecooling chamber I2 in turn in alinement with the discharge opening 48 ofthe furnace. Any suitable connection 58 maybe used for attaching thesection 48, adjacent the furnace, to the latter. Water is supplied toeach water chamber 44 through an inlet conduit 5| attached to the outertubular member 44 and is exhausted from the chamber through an exhaustconduit 52. The flow of water to the respective sections 48 may becontrolled by any suitable means such as termostatic valves and the like(not shown), so that any desired cooling temperature may be maintainedin the cooling chamber I2. Preferably the temperature in the coolingchamber I2 should be such that when the bimetal strip is discharged fromthe heat treating unit the temperature of the strip is below theoxidizing temperature. Moreover the temperature should be low enough sothat the strip can be readily handled and is ready for cold rollingwithout any further treatment.

The means for advancing the bimetal strip through the heating chamber IIand the cooling chamber I2 in this instance comprises two endlessflexible belts, an upper belt 53 and a lower belt 54 disposed andarranged in coplanar relation as best seen in Figure l. The upper belt53 is supported on pulleys 55 and 5'! supported at opposite ends of theheat treating unit. The lower belt is supported on pulleys 58 and 59also supported at opposite ends of the heat treating unit. The mountingpulleys for the upper and lower belt are arranged so that the bottomportion of the upper belt 53 and the top portion of the lower belt 54are adjacent each other in side by side relation and the bottom portionof the upper belt normally rests on the lower belt. With thisconstruction the belts are so arranged that a strip of metallic stockdisposed between the adjacent portions of the upper and lower belts isgripped sufllciently tight so that it is drawn along or advanced inunison with the corresponding gripping portions of the belts. Preferablythe belts 53 and 54 are of woven wire construction as best seen in Figs.6 and 11. The

pulleys 55 and 58 which are the drive pulleys are preferably providedwith a layer of friction material on their periphery so as to preventslippage between the pulleys and the flexible belts 53 and 54. Thepulleys 55 and 58 are mounted on shafts GI and 62 respectively supportedin suitable bearings mounted on opposite sides of the framework 48. Thetop portion of the belt 54 is supported by a bottom 63 of a mullle 55extending through the heating chamber II, the bottom of the coolingchamber l2 and a horizontally extending trough 65a at the charge end ofthe furnace unit, together forming a guide for the belt 54. As shown inFigs. 4 and 7 the muille 65 is supported by suitably capped spaced ribs55, projecting upwardly from the bottom of the chamber II and the endsof the furnace so that the mufile is held substantially centrally of thechamber II. The lower portion of the belt 54 is supported by guides 64,64a and 54b, beneath the he'attreatingunit and suitably supported by theframeworks 41 and 48 and by cross members 88 attached at their oppositeends to uprights 22 beneaththe furnace I5. Rollers 18 at opposite endsof'the heattreating unit also support the belt 54 and provide frictionfree surfaces for the belt. A tension roll 15 is mounted on theframework 48 to ensage the belt 54 adjacent the pulley 58. The upperportion of the top belt 53 is supported by troughshaped guides 51, 51aand 51b supported on top of the heat treating unit respectively by theframeworks 41 and 48 and cross members 58 on the housin l8 connected onOpp site sides to the uprights 22. Where desired the guides 54, 84a,64b, 61, 81a and 51b may be replaced by suitable rollers. The beltsSland 54 are arranged so that when they are not advancing a strip ofmetal the lower portion of the belt 53 normally rests on the top portionof the lower belt 54 as best seen in Fig. 11. To facilitate the placingof the bimetal strip between the conveying belts 53 and 54 the lowerbelt 54 extends forwardly of the charge end of the furnace asubstantially greater distance than the upper belt to define a table forreadily receiving the bimetal strip as shown in Figs. 1 and 3.

Provision is made for automatically adjusting the tension in the belts58 and 54. In this instance automatic tensioning thereof is effected bymeans of a weight. The tensioning means for the belt 53 is best shown inFigs. 3 and 5. Therein it is seen that the pulley 51 is supported on ashaft ll. The latter is supported at opposite ends in blocks 12supported between horizontally disposed ways I3 and 14 forming a part ofa support or framework 16 at the charge end of the heat treating unit.Attached to each block 12 is an eye 11. A chain I8 is secured at one endto the eye 'I'! and at its opposite end is connected to an eye in amember I8 supporting a weight 88. Between the eye I1 and the weight 88the chain loops over a sprocket 8| supported on an upright 82 of thesupport 15 and a sprocket 83 supported on an upright 84 of the supportI6 spaced from the upright 82. A turnbuckle 85 is connected in the chainI8 for adjustment purposes. The weight 88 is disposed between theframework 15 and the furnace I5. With this construction whenever thereis any change in the length of the belt 53, due to heating of the beltor as it passes through the heating chamber II or the like the weight 88will move downwardly thereby pulling the blocks I2 and in turn thepulley 51 to the left as shown in Fig. 3 and thereby assure that adesired tension is maintained in the belt 53. Contraction of the beltwill cause the weight 88 to be raised. Any desired tension may beobtained in the belt by changing the weight 88.

The tension in the belt 54 is automatically adjusted in the same manneras that described for the belt 53. In this instance the pulley 59 issupported on a shaft 9| supported at opposite ends by slide blocks 82.The latter are supported between horizontally disposed spaced ways 93and 94 forming a part of the framework 16. An eye 81 is connected witheach of the blocks and extends in a direction outwardly from the furnaceI5. Attached to each eye is a chain 98 which is connected at itsopposite end to an eye of a member 89 supporting a weight I88. Betweenthe eye 9'! and the weight I88 the chain 98 passes over a sprocket I8Isuit ably supported on an upright I82 of the framework 15 and a sprocketI83 supported on the upright 82 below the sprocket 8|. A turnbuckle misconnected in the chain for purposes of making adjustments. The weight Icauses the pulley 59 to be moved to the left upon ex-' the stretching ofthe belts. For thispurpose the framework 16 is mounted on suitableslides III' for movement lengthwise toward and away from the furnace I6.Disposed between the slides is a rigid block I01 rigidly fastened to thesame support as the slides III; Secured on the block I01 lsa nut I09."I'hreaded through the nut I08 is a screw I09 having a squared end H0.The squared end 0 is mounted in a bushing II2 for rotational movementbut is securely held against longitudinal movement. As shown the squaredend I I0 is positioned to be accessible from the extreme front end ofthe heat treating unit. The bushing H2 is supported on a suitable crossmember II3 supported by the spaced uprights I02. With this constructionrotation of the screw I09 by means of a wrench or crank attached to thesquared head H0 will cause the framework I6 to move towards or away fromthe charge end of the furnace depending on the direction of rotation ofthe screw I09 and thereby simultaneously adjust the tension in bothbelts.

The belts 53 and 54 may be driven by any suitable means. In thisinstance they are driven by a motor H6 mounted on a platform IIldisposed at one side of the heat treating unit (see Figs. 8 and 10). Themotor H6 is connected by a V-belt I20 to a speed change unit H8. Thelatter in turn is connected by a Vbelt H9 to a speed reducer I2I mountedon the platform H1. The speed reducer unit I2I is connected by means ofacoupling I22 to a shaft I23 suitably supported at opposite ends on theplatform I I1 and the framework 48. A spur gear I24 is mounted on theshaft I23. Meshingwith the spur gear I24 is a spur gear I26 mounted on ashaft I21 having its ends suitably supported by bearings mounted on theplatform H1 and the framework 48. A sprocket I20 is mounted on the shaftI21 in spaced relation to the spur gear I26 and is connected by means ofa chain I29 to a sprocket I3I mounted on the shaft 6|. Suitabletensioning means I35 may be provided for the chain I29. A sprocket I32mounted on the shaft I23 in spaced relation to the spur gear I24 isconnected by a chain I30 with a sprocket I33 mounted on the shaft 62.With this arrangement it will be seen that both belts are positivelysimultaneously driven through the pulleys 56 and'59 from the singlemotor H6. Suitable tensioning means for the chain I30 ma be provided ifdesired.

As the bimetal strip passes through the heat treating unit it distortsas it is first heated up. This distortion continues until after what canbe considered the critical temperature of the bimetal strip is reached.Thereafter additional heat. 1. e. a higher temperature has little or noeffect on the distortion of the bimetal strip.

8 The strip again becomes distorted when the strip passes from thetemperatures above the critical temperature down to a lowertemperature.- The amount of distortion decreases in this case with adecrease in temperature until at relatively low temperatures the bimetalstrip assumes its normal position in which it is relatively free fromdistortion. While the distortion of the stripxis the prime reason forits use in industry this'inherent .bending of the strip during theheating and cooling steps of the heat treating process has presented areal problem to the industry insofar as handling of it is concerned.Accordingly one phase of the invention is concerned with means forrestraining the distortion of the bimetal 'strip as it is advancedsuccessively through the heating chamber II and the cooling chamber I2.This is effected in this instances by limiting the permissible movementof the'bottom portion of the top belt 53 away from the upper portion ofthe lower belt 54. A top I36 of the muflie (see Figs. 4 and 7) and thebottom 63 is utilized for this purpose in this instance for restrainingthe defective movement in the heating chamber II. The distance betweenthe top portion I36 and the bottom 63 of the muflle 65 is suflicient toaccommodate both thicknesses of the belts 53 and 54 and a bimetal stripdisposed therebetween. sufficient clearance being provided to preventsticking of parts. In a similar manner the top and bottom portions ofthe inner tubular member 4I provide restraining or distortion limitingmeans for the belts in the cooling chamber I2. To lower the temperaturehead required in the heating chamber the bottom portion 63 and topportion I36 are preferably perforated. This allows for bettercirculation of heat between the heatin elements and the bimetallic stripcarried between the belts. A flexible wire belt construction formed asillustrated herein is also advantageous in'that hot air is permitted tocirculate freely about the bimetal strip as it passes through theheating chamber. The bottom 63 and the top I36 may be formed in separatesections secured together in any conventional manner or may be formed bya plurality of tubular members welded together at their ends as shown inFig. 4. v

A preselected atmosphere may be maintained in the furnace. Theparticular atmosphere may vary considerably for different materials asis well known in the art. Herein the gas for producing the atmospheremay be introduced into the heating chamber II from a header I39 (see Fi4) through branch lines I39a, I391), I390 and H911. As shown the headerI39 is mounted on top of the housing I9 and is connected to a gas supplyline I38. A valve I40 may be connected between the header I39 and theline I30 for control purposes. Preferably the branch lines are arrangedto be connected to the furnace unit at spaced positions therealong. Thusthe branch line I39a is connected to the-section I43 to be incommunication with the heating chamber I I at the forward end of thefurnace. The branch line I39d is connected to be in communication withthe passageway 43 at the discharge end of th furnace. The branch linesI39b and I390 are connected to the chamber II at positions intermediateth ends thereof.

Frequently atmospheres in a furnace are of a relatively explosivecharacter, particularly when mixed with proper-proportions of air. -Thisis particularly true when a hydrogen atmosphere is employed as is oftenthe case. Accordingly provision is made for preventing the'exhaust ofthis atmosphere into theroom in which the heat treating unit isdisposed. To this end both a felt seal I H and a gas curtain I42 areutilized at both ends of the heat treating unit to prevent the leakageof the atmosphere from the furnace. As best shown in Fig. 11 each feltseal I4I comprises an upper portion I43 and a lower portion I44. Theseportions are retained between flanges I41 and I48 on extensions I49 andI50 respectively of the muffle Qand project forwardly of the charge endoi the furnace It. The section I43 is formed with a stepped portion I 5I. With this construction the felts I43 and I44 engage the outer sidesof the belts, yet will not provide a friction surface which willinterfere with the movement of the belts. The upper felt rests on thetop portion of the upper belt 53. In the event of distortion of thestrip so that the belt is moved upwardly slightly the end of the feltI43 will be forced into the recess defined by the stepped portion III atthe top of the extension I43. The weight of the belts 53 and 54 normallyforces the extreme upper end of the felt I44 into the recess defined bythe stepped portion I5I. One position of the felts during op- One flameor gas curtain I42 is mounted at the end of the extension I50 and theother is mounted at the end of an extension I55 of the cooling chamberI2. In general the flame curtain comprises spaced tubularmembers I53having a plurality of ports I51 and closed at one end. At opposite endsthe tubular members I53 are held in assembled relation by suitablebrackets I54, which are attached to the frameworks I5 and 43respectively. Gas is supplied to the tubular members I53 by a suitableconnection, not shown. During the operation of the heat treating unitthe gas curtain burns continually and thus burns any gas such ashydrogen which escapes or leaks from the furnace. By having both thefelt seal HI and the gas curtain I42 it will be seen that effectively nofurnace atmosphere can escape into the room adjacent the furnace.

As an additional safeguard to operating personnel of the heat treatingunit conventional blowout ports I6I are provided adjacent the charge anddischarge ends of the furnace l5. In this instanc the blow-out port I5Iat the charge end of the furnace is formed in the section I49 betweenthe felt seal HI and the charge end of the furnace I8 (see Fig. '5) andthe other blow-out port I is located in the first section 40' of thecooling chamber I2 (see Fig.6).

The operation of the above fumaceisreadilyapparent but may be summarizedbriefly as follows: The strip of bimetal is placed on the table formedby the belt 54 at the charge end of the heat treating unit. As soon asthe belt 54 carries the bimetal forward a suflicient distance thebimetal is gripped securely between the two belts 53 and 54 and isadvanced first through the heating chamber I I and then through thecooling chamber l2. As the bimetal heats up in the heating chamber I Iit tends to distort. This distortion of the bimetal causes the adjacentportions'of the belts 53 and 54 to spread apart. The distance which thebelts may be spread however is limited in this instance by the top I36and bottom 53 of the inuiiie 65. In effect the deflection movement ofthe strip is limited. When the temperature in the heating chamber IIgoes above the critical temperature of the bimetal strip, the forcescausing the iseration of the heat treating unit is shown in Fig.

10 tortion are at a minimum and the weight ofthe upper belt itself isprobably suiiicient to limit the distorting movement of the bimetalstrip- However when the bimetal strip is cooled from the hightemperature through the critical temper-a ture to a low temperature inpassing through the cooling chamber so that it can be readily handied,the bimetal strip is again distorted. This relatively flat piece ofmaterial that is ready for the cold rolling process.

This construction is adaptable for other types of material besidesbimetal. The construction described herein may be operated by oneperson. One of the important advantages of this furnace construction isthat the cost of handling bimetal isgreatly decreased and consequentlythe per'unit cost of bimetal is greatly reduced.

While I have shown one embodiment of my invention I do not wish to belimited thereto since many modifications may be made and I thereforecontemplate by the claims to cover such modifications as fall within thetrue spirit and scope of my invention.

Iclaim:

1. In a furnace for annealing a bimetal and the like strip material thatdistorts on heating, the combination of a heating chamber. a pair ofopposed flexible belts having movable portions disposed in said chamberand spaced apart to receive a strip of said material therebetween andconvey the same through said heating chamber. and means associated withsaid belts and disposed above and below said movable belt portionscapable of engaging said belts at an infinite number of points along thelength of said heating chamber upon distortion of said strip material tohold said belts in a predetermined spaced relation to limit warpage ofsaid strip as it passes through said heating chamber.

2. In a heat treating unit for annealing bimetal and the likestripmaterial that distorts on heating, the combination of a furnacehaving a heating chamber therein. a first endless flexible metal belthaving a portion extendingwthrough said heating chamber, means on theoutside of said chamber for mounting and driving said belt,

a second endless flexible belt having a portion extending through theheating chamber adjacent said portion of the first endless belt todefine gripping means to secure a strip of material and advance itthrough the heating chamber, means on the outside of said chamber formounting and driving said second belt, and means encasing said portionsof the endless belt in the heating chamber to guide the belts, said lastmentioned means being continuous in extent throughout said heatingchamber and capable of engaging said belts at an infinite number ofpoints therealong and being so dimensioned to limit the separation ofsaid belts to a predetermined amount upon distortion of the strip as thelatter advances through the heating chamber.

3. In a heat treating furnace unit for bimetal and the like stripmaterial that distorts on heat ing, the combination of' a heatingchamber, a cooling chamber, a pair of flexible endless metallic beltshaving portions in said heating and l1 cooling chambers in opposedrelation to define a gripping means for advancing a strip of saidmaterial through the heating and cooling chambers respectively, andrigid means extending for 3 at least the length of said heating chamberencasing said portions and forming a guide for said portions forlimiting at any point therealong relative displacement of said portionsaway from each other whereby to limit the distortion of said strip ofmaterial.

4. The combination recited in claim-3 including means for continuouslyapplying a predetermined tension in each of said belts.

5. The combination recited in claim 3 with manual means forsimultaneously adjusting the tension in both belts.

6. In a heat treating furnace unit for bimetal and the like materialthat distorts on heating, the combination of a heating chamber. acooling chamber, a pair of flexible endless metallic belts havingportions in said heating and cooling chamber in opposed relation todefine a gripping means for advancing a strip of material through theheating and cooling chambers respectively, means for continuouslyapplying a predetermined tension to said belts, manual means forsimultaneously adjusting said last mentioned means, and rigid meansextending throughout the length of said furnace unit for completelyencasing said portions thereby forming a guide for said portions andlimiting at any point therealong relative displacement of the belts awayfrom each other to limit the distortion of said strip.

7. In a heat treating furnace unit for bimetal and the like stripmaterial, the combination of a furnace having an elongated heatingchamber, a muille extending through said chamber having a passagewaytherethrough defined by top and bottom surfaces in closely spacedrelation, an elongated cooling chamber in alinement with said passagewaydefined in part by top and bottom surfaces in closely spaced relationand forming a continuation of the top and bottom surfaces of the muiile,a pair of flexible endless belts having portions extending through saidpassageway and said chamber in adjacent relation defining opposedgripping surfaces for holding a strip of material, pulley means on theoutside of said heating chamber and said cooling chamber for mountingsaid belts, and driving means for driving said pulley means to advancesaid gripping surfaces successively through the heating chamber and thecooling chamber, said top and bottom surfaces defining continuousrestraining means engageable with said belts respectively to limit thedistortion of said strip as it passes through the heating and coolingchambers.

8. The combination recited in claim 7 in which a portion of the muflieis perforated.

9. In a heat treating unit for bimetal and the like material, thecombination of a treating chamber having openings at opposite ends andadapted to contain an atmosphere, a pair of endless belts havingportions movable through said chamber in overlying relation to definetop and bottom gripping portions for advancing a strip of materialthrough said chamber, tubular means encasing substantial length of saidportions of 12 the belts defining a guide ton-said portions of thebelts, said tubular means defining continuous restraining means forlimiting distortion of said strip as it passes through said chamber, andresilient felt seal means mounted on said tubular means to be engageablewith the top and bottom portions of the belts respectively to minimizeleakage of atmosphere through said openings for any relative position ofthe belts due to distortion of the strip.

10. The combination recited in claim 9 in which a gas curtain is inspaced relation with each of said felt seal means and together with saidfelt means effectively prevents leakage of furnace atmosphere to theatmosphere surrounding the heat treating unit.

11. The combination recited in claim 9 in which the felt seal means haveends projecting inwardly of the topand bottom portions of the tubularmeans to engage the top and bottom portions of the belts respectivelyand in which the top and bottom portions of the tubular means are formedwith recesses to receive the end portions of the felt seals when thebelts are in side by side sliding movement with the top or bottomportions of the tubular means respectively to provide substantiallyfriction free surfaces for said portions of the belts.

12. In a furnace for annealing relatively short lengths of stripmaterial such as a bimetallic material that distorts when subjected totemperature changes, the combination of a chamber for causing asubstantial change in temperature of said strip material when passingtherethrough, a pairof opposed flexible belts having movable portionsdisposed in said chamber and spaced apart to receive a strip of saidmaterial therebetween and convey the same through said chamber, andmeans associated with said belts extending continuously through saidchamber and disposed above and below said movable belt portions toengage said belts upon distortion of said strip material at an infinitenumber of points therealong to hold said belts in a predetermined spacedrelation to limit distortion of said strip as it passes through saidchamber.

13. The combination recited in claim 12 in which the flexible beltspermit air circulation therethrough.

DONALD H. GARDNER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 890,252 Thompson June 9, 19081,319,085 Jacobson Oct. 21, 1919 1,367,049 Jackman et al Feb. 1, 19211,714,040 Naugle et al May 21, 1929 1,753,828 Greer et al. Apr. 8, 19302,061,910 Kingston Nov. 24, 1936 2,101,065 Hayes Dec. 7, 1937 2,237,966Koehring Apr. 8, 1941 2,319,300 Cook May 18, 1943

